It is known to provide endoluminal grafts or endografts for treating vascular lesions or pathologies such as aneurysms, stenosis, dissections, and others using minimally invasive surgical techniques. A conventional endograft is typically radially compressed or constrained, mounted on a deployment catheter, introduced into the vasculature, and advanced to its intended deployment site. Such conventional endografts, as is known in the art, typically include a metal lattice element (stent) which provides an expansile force and a fabric (graft) designed to contain pressurized bloodflow within its lumen, thereby excluding bloodflow from the site of the vascular pathology or lesion. As is known, the stent and graft portion of the endograft are typically attached one to the other or incorporated one with the other, leading to the common nomenclature “stent graft.” Suitable materials for fabricating such endografts are well known in the art.
Typically, endografts are introduced into the vasculature from a location remote from the intended treatment zone, for example a femoral artery. The endograft must then be positioned and deployed so with the graft proximal and distal ends bracketing the vascular lesion, further whereby each graft end is positioned in a healthy portion of the blood vessel being treated, to provide an occlusive seal. This allows exclusion of the systemic blood pressure from the diseased blood vessel segment. Inaccurate placement of an endograft can result in ischemic complications from unintended coverage of branch vessels, or incomplete exclusion of the pathology being treated because of minimal apposition of the endograft and the vessel wall in the sealing zone. Further complicating the issue, the intervening healthy “landing zone” between the vascular pathology and potentially important branch blood vessels is often very short.
In cases such as minimal “landing zones” for proper placement of an endograft, the ability to re-position the device prior to final placement can improve accuracy and greatly improve the odds of safe and effective exclusion of the diseased vascular segments. However, during deployment, endografts are subjected to the displacement forces of the pressurized bloodflow in the vessel being treated, creating a “windsock” effect. Such displacement forces continue until the endograft is fully deployed or opened and blood flow is established through the endograft lumen. For conventional single piece endografts, however, at that point the endograft has been disconnected from the positioning device (such as a deployment catheter) and cannot be repositioned.
Strategies have been proposed for overcoming this problem. These include temporarily arresting bloodflow (for example by arresting the heart). However, this poses a significant patient risk. Another strategy considered is partially constraining the endograft longitudinally during deployment. However, a single piece endograft that is partially constrained longitudinally is still significantly detached from its deployment catheter, limiting the repositioning force that can be applied to the graft by manipulation of its deployment catheter at the remote introduction site.
There has accordingly been identified a need in the art for an endoluminal graft which, while effective for its intended purpose, provides additional advantages in allowing repositioning during placement in a diseased blood vessel, to ensure the best positioning of the device to isolate the vascular pathology being treated.